A FILMLESS METHOD AND APPARATUS FOR PRODUCING 3-D PHOTOGRAPHS

Abstract: A filmless 3-D photographic print process (figure 7) in which images displayed on a video monitor (1) are used in place of negatives (4) and the illuminating lamphouse (5) of a photographic printer (figure 4). With this process, the displayed images are directly exposed through a printing lens (6) onto 3-D print material (7) which is a lenticular screen pre-coated with a photographic emulsion. This direct exposure method makes instant 3-D photography possible. This method and apparatus can be used to print computer generated graphics and images of scenes.

Description: A FILMLESS METHOD AND APPARATUS FOR PRODUCING 3-D PHOTOGRAPHS BACKGROUND OF THE INVENTION Three-dimensional (3-D) modeling is one of the most important aspects of computer generated graphics where generated images of scenes or objects are represented with depth, or the third dimension. 3-D modeling has numerous scientific and industrial applications, ranging from molecular modeling to computer-aided design (CAD). For example, computer-aided design systems allow their users to manipulate model of machined components, automobile bodies and aircraft parts; molecular models provide chemists a tool for studying molecular behavior. Since its emergence from the 1960's to the present time, computer 3-D modeling has become a mature imaging technique. However, the display technology that is required to present the generated images to the viewers has not shared the same progress. To date, the display of 3-D images is still carried out mostly on a 2-D device, namely, the video monitor. In order to produce the third dimension on a 2-D display, computer generated graphics are usually presented in a time sequence such that the object is rotated to reveal its different facets, as illustrated in Fig. 1. To achieve a realistic presentation of a rotating object, computer graphics are usually generated in a large number of frames, each of which shows an object as viewed at a slightly different angle, so that the rotation will not appear jittery. With this kind of time-sequenced display, one must have access to a suitable graphic system to see the depth in the computer generated graphics. For those who do not have immediate access to such systems, the lenticular- type 3-D photography is presently the only viable alternative for 3-D viewing. 3-D photographs are relatively inexpensive and easily produced in large quantities. They can be distributed by mail. They can be inserted in books and magazines. In present 3-D photography, it is necessary to first take a series of pictures of the object from different vantage points. It is then necessary to develop the negatives and print the different scenes onto lenticular print material. It is highly desirable to be able to print the 3-D photographs without the use of film. PRIOR ART The conventional method for producing lenticular-type 3-D hard copies from computer generated graphics is basically the same as that for producing 3- D photographs of real objects or scenes. The conventional method has been disclosed in a number of patents and notably U.S. Patent 3,953,869 (Wah Lo, et al.) This method is briefly described herein with reference to Fig. 2 to Fig. 5. Fig. 2 shows a single-lens camera being used for recording the graphics displayed on a video monitor onto a photographic film. With this image recording method, while a sequence of computer generated graphics representing objects as viewed at different angles are displayed on the monitor screen, the camera exposes a series of 2-D images on the film. A series of 2-D negatives so produced are illustrated in Fig. 3. It should be noted that even though computer graphics are usually generated in a large number of frames, only a fraction of them are recorded on film for practical reasons. Fig. 3 shows a series of three frame images. The composition of a 3-D photograph from a series of 2-D negatives is usually carried out by a method similar to that discussed in a number of disclosures such as U.S. Patent NO. 3,953,869 (Wah Lo, et al.), No. 4,903,069 (Lam) and 4,120,562 (Lo, et al.). In essence, for composing a 3-D photograph from a plurality of negatives, each of the negatives is exposed onto the print material at a different angle, as shown in Fig. 4. With this method, a scanning mechanism is used to laterally transport the printing lens and print material over a certain range so that an appropriate portion of the photographic emulsion under the lenticular screen is exposed with each negative, as later explained with reference to Fig. 5. During the printing process, the scanning mechanism must pause a number of times to allow a negative to be carried into the exposing position after its preceding negative is exposed. After all negative frames are exposed, the photographic emulsion under the lenticular screen will be filled with a series of compressed 2-D images. A cross section of the image-filled print material is shown in Fig. 5. Basically, a lenticular screen is a large array of cylindrical lenses and the screen is coated with a photographic emulsion to become a 3-D print material. Because of the focusing properties of cylindrical lenses, parallel light rays encounter each cylindrical lens will be compressed into a narrow strip at the focal plane which coincides with the base of the cylindrical lens. In order that a 3-D print can be viewed at any angle, the entire width of the cylindrical lens base must be filled with compressed images. For example, if three negatives are used to compose a 3-D photograph, then the scanning mechanism must transport the printing lens and the print material so that each negative exposes one-third of the base of the cylindrical lens. When the composite 3-D photograph is viewed, because of the focusing properties of the cylindrical lenses, only one image can be seen at a certain viewing angle. For this reason, each of the two eyes of a viewer will see a different 2-D image under the lenticular screen, as shown in Fig. 6. Ideally, the number of 2-D negatives used for composing a 3-D photograph should be large to produce a flicker-free 3-D image. Due to practical reasons, as mentioned earlier, this number is usually kept small, say, from 3 to 6. Thus, even though computer graphics are generated in a large number of frames, the majority of which are not used in the composition of a 3- D photograph is one adopts the conventional printing method. SUMMARY OF THE INVENTION It is an objective of the present invention to provide a method for producing 3-D hard copies from 3-D graphics generated by a computer. In particular, the method, according to the preferred embodiment of the present invention, allows the computer generated graphics displayed on a video monitor to directly expose the lenticular-type print material through a printing lens. Thus, this disclosed method does not require the use of photographic films. More importantly, according to the preferred embodiment, the lenticular-type print material used for producing 3-D photographs is pre-coated with a photographic emulsion so that there is no need for a laminating process in which a lenticular screen is attached to the photographic emulsion after the latter is chemically processed. In other words, the lenticular screen and the photographic emulsion are integral parts of the 3-D print material. It is a further objective of the present invention to provide an apparatus that has a capacity to produce 3-D hard copies from computer generated graphics in accordance with the aforementioned objective. The printing method, according to the present invention, is a one-step process which transfers images on a video screen directly through a lenticular screen onto a pre-coated photographic emulsion of the print material. This process makes instant 3-D photography possible if the pre-coated photographic emulsion is suitable for instant processing. As mentioned earlier, 3-D modeling computer generated graphics intended for time-sequenced presentations usually contains a large number of graphic frames. All, or a large number, of these graphic frames can be used to compose a 3-D photograph. For this reason, the method, according to the present invention, also improves the quality of 3-D photography as it can produce virtually flicker-free 3-D photographs. Briefly, this invention shows using a color video monitor and the images displayed thereon in place of the negatives and the illuminating lamphouse of a photographic printer. As shown in Fig. 7, a scanning mechanism is used to laterally transport the printing lens and the print material over a certain angular range so that each displayed image is exposed onto a portion of the photographic emulsion. It should be noted that because no negatives are involved in the printing process, there is no need for the scanning mechanism to pause after the exposure of each image frame is completed. In this printing method, the change of image frames is carried out electronically. The scanning mechanism, as shown in Fig. 7, transports the printing lens and the print material from left to right. Alternatively, a black-and-white monitor is used for the display of computer generated graphics. As shown in Fig. 8, the printing of each graphic frame requires three separate steps each of which uses one of the three color filters in a red/blue/green filter assembly placed in front of the printing lens. It is well-known that a color image on a color monitor is composed of three component images of additive primary colors: red, green and blue. In this alternative printing method, one component image of a frame is displayed at a time on a black-and-white monitor and a corresponding filter is selected to provide a proper single-color image to be exposed onto the print material. This filmless printing process can also be used to compose 3-D photographs of real objects. As shown in Fig. 9, an electronic imager is used to capture the images of an object at different viewing angles, the captured images can be directly channeled to the video monitor or they can be stored in an image storage/processing means before being transferred to the monitor. In this extended method, the printing process is identical to the process used in the aforementioned methods for producing 3-D hard copies from computer generated graphics, as described with reference to Figs. 7 and 8. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a video monitor being used to display computer generated graphics of an object at different angles. Fig. 2 shows a single-lens camera being used to capture the images displayed on a video screen. Fig. 3 shows a series of 2-D negatives presenting three different frames of computer generated images as viewed at different angles. Fig. 4 shows three printing angles for exposing three 2-D negatives onto a lenticular-type printing material, according to a conventional 3-D composing method. Fig. 5 shows the cross section of a plurality of cylindrical lenses and the exposed photographic emulsion underneath three of the lenses. Fig. 6 is a schematic diagram showing that when a 3-D photograph is viewed, a different 2-D image is presented to each of the viewer's eyes. Fig. 7 shows a filmless printing system where computer generated graphics of an object as viewed at different viewing angles are displayed on a color video monitor and a printing lens is used to expose the displayed image onto the print material at different printing angles. Fig. 8 shows an alternative printing scheme is which red, green and blue component images of a color graphics are displayed separately on a black and white monitor. A red/green/blue filter assembly is used to select and expose the proper single-color images onto the print material. Fig. 9 is a schematic diagram of a filmless printing system where the images of an object as viewed at different angles are captured by an electronic imager and stored in an image storage/processing device. The captures images are channeled to the video monitor for display. DETAILED DESCRIPTION Fig. 1 shows a computer image display system in which reference numeral 1 denotes a video monitor which displays images generated by a computer 2. Numerals 11, 12 and 13 denote displayed computer generated graphics as viewed at different angles. If the computer generated graphics are displayed in a time-sequence, the images show an object in rotation and thus reveal different facets of the same object. In Fig. 2, a single-lens camera 3 is used tote pictures of images displayed on the video monitor 1. It is understood that a selected sequence of computer generated images are displayed on the monitor so that these images are exposed onto a plurality of frames on the photographic film in the camera. Fig. 3 shows a strip of negative denoted by number 4, showing three different negative frames, denoted by numerals 33, 32 and 33. On the negative frames are three images: 21, 22, and 23, corresponding to the displayed images 11, 12 and 13 in Fig. 1. Fig. 4 shows the exposing of three 2-D negatives for composing a 3-D photograph according to a conventional method. In Fig. 4, numeral 5 denotes a lamphouse for illumination which projects the images on the negative strip 4 through a printing lens 6 onto a lenticular-type printing material 7. As illustrated, three 2-D images 21, 22 and 23 are separately exposed at three different angles, resulting in three corresponding images 71, 72 and 73 on the print material. The printing lens and print material is transported by a scanning mechanism, which is not shown, so that the exposure of each negative covers an appropriate portion of the lenticular screen as shown in Fig. 5. After the exposure of one negative is completed, the scanning mechanism must pause to allow another negative to enter the exposing position. Fig. 5 shows the cross section of a plurality of cylindrical lenses on the print material 7. The cylindrical lenses are collectively denoted by numeral 8. In this illustration, three 2-D negatives are used to compose a 3-D photograph. Thus, the photographic emulsion underneath each of the cylindrical lens must be filled with the compressed images of three negatives in three equal sections. In Fig. 5, numerals 81, 82 and 83 denote the compressed images under each cylindrical lens, corresponding to three 2-D images 21, 22 and 23. The compressed images 81, 82 and 83 represent parts of the images 71, 72 and 73 in Fig. 4. Fig. 6 is a schematic diagram showing a 3-D photograph being viewed by a person. As shown, each of the viewer's eyes sees a different 2-D image. In the figure, eye 50 sees the image denoted by numeral 44 while eye 51 sees image 42. Because image 42 and image 44 are images of the same object as viewed at different angles, they are a stereoscopic pair. Fig. 7 shows a filmless printing system for producing 3-D hard copies from computer generated graphics, in accordance with a preferred embodiment of the present invention. Numeral 1 denotes a video monitor which displays computer images of an object as viewed at different angles. In essence, the images displayed on the video monitor take place of the images 21, 22 and 23 shown in Fig. 4, but the exposing process is basically the same as the conventional method. As shown in Fig. 7, printing lens 6 is used to project the displayed images on video monitor 1 onto a lenticular-type print material 7. Similar to the exposing process shown in Fig. 4, scanning mechanism, which is not shown, transports the printing lens and the print material over an appropriate range so that the base of the lenticular screen is filled with compressed images. However, in this filmless printing system, the image frames on the monitor are changed electronically. Thus, the scanning mechanism does not need to pause for frame changing and the exposure can be carried out continuously during the entire printing process. If desired discontinuous scanning can be used which may be desirable if only a few views are to be printed. It is understood that the video monitor is connected to a computer that generates graphics or stores images. Fig. 8 shows an alternative printing scheme in which red, green and blue component images of a color graphics are displayed sequentially and separately on a black and white monitor, denoted by numeral 11. A red, green and blue filter assembly 9 is used to transmit a proper color for each of three component images for exposure. The rest of the printing process is basically the same as that described in the detailed description of Fig. 7. Fig. 9 is a schematic diagram of a filmless printing system similar to that described in the detailed description of Fig. 7, except that the 2-D images displayed on the video monitor are not generated by computer. In the embodiment shown in Fig. 9, the 2-D images displayed on the video monitor 1 are images of a real object. The images are captured by an electronic imager positioned at different horizontally-spaced vantage points, denoted by A, B and C. The captured images can be directly channeled to the video monitor 1 for display, or they can be stored in an image storage/processing means, 16, so that the stored images can be retrieved and channeled to the video monitor for printing at a later time. In printing a 3-D photograph in accordance with the present invention, the electronic imager can be moved to different vantage points or the object can be rotated. In either of these methods, the process can be either continuous or discontinue scanning. While the present invention has been described with reference to the preferred embodiment, it shall be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. Therefore, it is intended that the present invention shall include embodiments falling within the scope of the appended claims.

Claims: CLAIMS 1. A filmless photographic direct method of printing a three- dimensional image of an object in a continuously changing perspective onto lenticulated print material in which: (a) a sequence of two-dimensional video images are displayed in sequence on a video monitor in which the images are maintained in proper registration on the monitor; (b) the sequence of two-dimensional video images is projected and printed in sequence onto lenticulated print material by a printing lens focused onto the images displayed on the video monitor. 2. The method of Claim 1 in which the video images displayed on the video monitor are taken by electronic imager from different viewpoints. 3. The method of Claim 2 in which a single electronic imager is positioned and moved relative to the object to scan and take a sequence of images of the object from several viewpoints and in which the video images are projected and printed in sequence by scanning onto the lenticulated print material. 4. A filmless photographic direct method of printing a three- dimensional image of an object in a continuously changing perspective onto lenticulated print material in which: (a) a sequence of computer-generated images are displayed in sequence on a video monitor in which the images are maintained in proper registration on the monitor; (b) the sequence of video images is projected and printed in sequence onto lenticulated print material by a printing lens focused onto the images displayed on the video monitor. 5. A filmless photographic apparatus for composing a three- dimensional image in continuously changing perspective onto lenticulated print material which comprises: (a) at least one electronic imager for taking a sequence of video images; (b) a video monitor for displaying and maintaining in proper registration the sequence of video images taken by the electronic imager; (c) a printing lens for projecting and printing the video images displayed on the video monitor in sequence on lenticulated print material. (d) a scanning mechanism for transporting the lenticulated print material and the printing lens over the necessary range in the printing process. 6. The apparatus in Claim 5 in which the electronic imager is designed to take a sequence of video images of an object from different viewpoints. 7. The apparatus of Claim 6 in which an electronic imager is positioned and moved relative to the object to scan and to take a sequence of images of the object from several viewpoints. 8. A filmless photographic direct method of composing a three- dimensional image of an object in a continuously changing perspective onto lenticulated print material in which: (a) A sequence of video images are taken by at least one electronic imager and separated into three monochrome colors and displayed in sequence in one of the monochrome colors on a video monitor in which the images are maintained in proper registration; (b) the video images are projected and printed onto lenticulated print material by a printing lens which is focused onto the images displayed on the video monitor.

Inventors: LO ALLEN KWOK WASH, LO, ALLEN, KWOK, WASH
Applicants: IMAGE TECHNOLOGY INT, IMAGE TECHNOLOGY INTERNATIONAL, INC.
Application year: 1994
Main classification: G06F15
IPC codes: G02B27, G03B33, G03B35, G06K15, H04N1